Search results for "Oxygen tension"
showing 10 items of 37 documents
Corneal Oxygen Supply Conditions
1976
Pronounced cornea hypoxia induces swelling and a loss of transparency. Hypoxia of longer duration causes necrosis, particularly of the corneal endothelium. These findings were observed after ligation of the cilial arteries and the arteria carotis interna, after reduction of oxygen tension on the anterior corneal surface as well as after prolonged wearing of ill-fitted contact lenses (11, 15, 18, 22, 23). Because the normal function of the corneal endothelium plays a central role in maintaining transparency, an insufficient endothelial oxygen supply can directly influence vision (3, 17).
Novel technologies to detect atelectotrauma in the injured lung
2010
ABSTRACTCyclical recruitment and derecruitment of lung parenchyma (R/D) remains a serious problem in ALI/ARDS patients, defined as atelectotrauma. Detection of cyclical R/D to titrate the optimal respiratory settings is of high clinical importance. Image-based technologies that are capable of detecting changes of lung ventilation within a respiratory cycle include dynamic computed tomography (dCT), synchrotron radiation computed tomography (SRCT), and electrical impedance tomography (EIT). Time-dependent intra-arterial oxygen tension monitoring represents an alternative approach to detect cyclical R/D, as cyclical R/D can result in oscillations of PaO2 within a respiratory cycle. Continuous…
340 EPIGENETIC ANALYSIS OF DEVELOPMENTALLY IMPORTANT GENES IN BOVINE OOCYTES OF DIFFERENT ORIGINS
2010
A critical step in assisted reproductive technologies (ART) is the IVM of oocytes. The quality of the oocyte is crucial for successful fertilization and subsequent embryo development. Studies in bovine ART, and epidemiological studies in children from ART, reveal a degree of abnormal development thought to be primarily caused by aberrant DNA methylation patterns in imprinted and non-imprinted genes. Due to the inherent similarities in bovine and human preimplantation embryonic development, bovine oocyte and embryo development is increasingly being used as a model for human development. The goal of this project is to investigate the effects of specific IVM conditions on the DNA methylation …
Changes in O2 Consumption of Multicellular Spheroids During Development of Necrosis
1985
Multicellular spheroids are spherical aggregates of cells that are supplied by diffusion of oxygen and substrates from the surrounding growth medium (Sutherland and Durand, 1976). Metabolic waste products are removed from the cells in these aggregates by diffusion into the growth medium. Cells within multicellular spheroids may be exposed to environmental conditions similar to those in tissue located between nutritive microvessels. Thus, tumor spheroids make it possible to study the impact of the tumor-specific micromilieu on cellular metabolism, cell cycle state, cellular viability or response to treatment. Factors in the microenvironment of tumor cells which may be relevant in this regard…
Comparative Studies on Vascular Endothelium in vitro
1994
Recent studies have presented evidence that the processes of hypoxaemia and reperfusion are involved in several pathogenetic mechanisms of atherosclerotic lesions. The ability of hypoxaemia to activate circulating white blood cells (WBCs) and enhance WBC-endothelial cell (EC) interactions is suspected to be a major factor in deleterious processes in the blood vessel wall. Various groups have suggested that cell adhesion molecules (CAMs), such as ICAM-1, VCAM-1 and E-selectin and their leukocyte ligands are involved in intercellular activities of the relevant cell types. We studied the effects of different oxygen tensions, simulating normoxic conditions, hypoxia and hyperoxia in vitro with t…
Comparative Studies on Vascular Endothelium in vitro
1995
Recent studies have presented evidence that the processes of hypoxaemia and reperfusion are involved in several pathogenetic mechanisms of atherosclerotic lesions. The ability of hypoxaemia to activate circulating white blood cells (WBCs) and enhance WBC-endothelial cell (EC) interactions is suspected to be a major factor in deleterious processes in the blood vessel wall. Various groups have suggested that cell adhesion molecules (CAMs), such as ICAM-1, VCAM-1 and E-selectin and their leukocyte ligands are involved in intercellular activities of the relevant cell types. We studied the effects of different oxygen tensions, simulating normoxic conditions, hypoxia and hyperoxia in vitro with t…
Tumor tissue oxygenation as evaluated by computerized-po2-histography
1990
A computerized pO2 measurement system with a novel electrode motion pattern (Sigma-pO2-histography) was evaluated in vitro and in vivo. The system was found to be reliable in 0.9% saline and 10% hydroxyethylene starch solution and in fresh donor blood. Marked deviations were found in lipid and hemoglobin solutions and in fluorocarbon emulsions. Histograms obtained in rat liver, mouse muscle, and subcutis were similar to previously reported distributions. Direct comparison between Sigma-Eppendorf and self-constructed Whalen-type electrodes in hypoxic tumors gave similar results. A large series of measurements indicated that hypoxic and anoxic tissue areas were frequently found both in isogra…
Microelectrode Measurements of Oxygen Tension Distributions in Multicellular Spheroids Cultured in Spinner Flasks
1984
Since multicellular spheroids were introduced into cancer research by Sutherland et al. (1970, 1971), they have been widely used for studying the susceptibility of cancer cells to various treatment modalities. Many of these investigations provided evidence for a major role of oxygen in controlling the metabolic and cell cycle state of the tumor cells, thus modifying the responsiveness of the cells to therapy. Several investigators have measured O2 tension (PO2) distributions in spheroids with O2-sensitive microelectrodes (Carlsson et al. 1979; Kaufman et al. 1981; Mueller-Klieser and Sutherland 1982a, b, 1983; Mueller-Klieser et al. 1983). The measurements produced PO2 values that varied co…
Geo-economic variations in epidemiology, patterns of care, and outcomes in patients with acute respiratory distress syndrome: insights from the LUNG …
2017
Background Little information is available about the geo-economic variations in demographics, management, and outcomes of patients with acute respiratory distress syndrome (ARDS). We aimed to characterise the effect of these geo-economic variations in patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE). Methods LUNG SAFE was done during 4 consecutive weeks in winter, 2014, in a convenience sample of 459 intensive-care units in 50 countries across six continents. Inclusion criteria were admission to a participating intensive-care unit (including transfers) within the enrolment window and receipt of invasive or non…
Noninvasive Ventilation of Patients with Acute Respiratory Distress Syndrome: Insights from the LUNG SAFE Study
2016
Rationale: Noninvasive ventilation (NIV) is increasingly used in patients with acute respiratory distress syndrome (ARDS). The evidence supporting NIV use in patients with ARDS remains relatively sparse.Objectives: To determine whether, during NIV, the categorization of ARDS severity based on the PaO2/FiO2 Berlin criteria is useful.Methods: The LUNG SAFE (Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure) study described the management of patients with ARDS. This substudy examines the current practice of NIV use in ARDS, the utility of the PaO2/FiO2 ratio in classifying patients receiving NIV, and the impact of NIV on outcome.Measurements and Main…